Let's clean up NAV #3 - AltSearchField

With RTC all of a sudden, so it seemed to many, AltSearchField was not working anymore. Complaints abundant as probably the same 'many' hadn't learned about the new dropdown list yet. You know that list defined by the FieldGroup property on a table.

Meanwhile this dropdown list has become a common feature that provides the user with even a more powerful way of searching the correct data than AltSearchField did provide. And still AltSearchField is to be found in C/SIDE as a table property including the data that it was populated with in the past. However, totally obsolete now and a next candidate to be cleaned out!